Agreed. If you are selling or making a one size fits all, simple is WAAAAY better.
But for you and I it's just one painful experience and it's over. I like the simplicity and lack of interference of a sensor up top on the big gear. You would have to ratio it, but could you put yours on the small gear?
As already stated, I'll prolly do something like you are planning until I get into my head enough to be able to make something better.
Regarding the one size fits all approach...
Our device is programmed to work with a simple hall effect sensor which supplies the microcontroller with a single wire carrying hall voltage signal having a square waveform that triggers in response to a passing magnetic fields, ie our magnet array. In our device the speed is calculated based on the set number of pulses per revolution and interval between the pulses.
As such, in order to use our device to sense the proximity and speed of gear teeth, the selection of a sensor requires some care to select a compatible sensor that
reliably outputs a similar variable hall voltage in the same range as the original hall effect sensor. Normally open, 5 to 30 volts, 150-250 mA. There are plenty of proximity sensors that are normally open circuit and that will output a square wave voltage signal, and the cheap inductance sensors you can find on amazon will often fit the bill. But being cheap I question the reliability of the oscillator circuit that converts the varying inductance into the square wave output.
In my case though I did not want to rely on sensors of such dubious quality so I selected a product type with a different trigger mechanism and of far higher quality. I was referring to a specific type proximity sensor that detects gear teeth based on a hall effect sensor, and a permanent magnet that supplies a biased magnetic field. the hall effect sensor triggers when interacting with an external ferrous target, ie the gear teeth. The Phoenix America Series P5000 and the Omega OMDC-MPU-A. They're about 25 times the price, but they also are far far less likely to miss a tooth which would be disastrous when the program calculates speeds based on interval between the teeth passing the sensor.
I'm sorry for contributing to the confusion around proximity sensors. I hope this leaves everyone with a better understanding of the types of products available.
